There is an ongoing need for electrical connector apparatus (and methods of electrically connecting apparatus), that provide reliable electrical connection. There is also an ongoing need for electrical connector apparatus (and methods of electrically connecting apparatus), that provide reliable electrical connection as well as reliable mechanical connection. There is also an ongoing need for these types of electrical connector apparatus (and methods of electrically connecting apparatus), that are simple to electrically connect. There is also an ongoing need for these types of electrical connector apparatus (and methods of electrically connecting apparatus), that can be connected in small spaces. There is also an ongoing need for these types of electrical connector apparatus (and methods of electrically connecting apparatus), that can be employed in the context of retrofitting replacement apparatus into existing apparatus (e.g., replacing apparatus that comprises one or more light emitters with new apparatus that comprises one or more new light emitters, e.g., one or more solid state light emitters such as light emitting diodes).